Grinding machine



Nov. 1, 1955 o. E. HILL 2,722,088

GRINDING MACHINE Filed Feb. 8, 1954 5 Sheets-Sheet l INVENTOR. O/ VA E.HILL Nov. 1, 1955 o. E. HILL 2,722,088

GRINDING MACHINE Filed Feb. 8, 1954 5 Sheets-Sheet 2 I VENTOR. O/VA HILLHTTOENEY Nov. 1, 1955 o. E. HILL 2,722,083

GRINDING MACHINE Filed Feb. 8, 1954 5 Sheets-Sheet 5 /4 Fig.3 35C: 2

INVENTOR. 01 VA E. H// L H TTOENE Y Nov. 1, 1955 o. E. HILL 2,722,088

GRINDING MACHINE Filed Feb. 8, 1954 5 Sheets-Sheet 5 C INVENTOR. O/l/HH/LL United States Patent GRINDING MACHINE Oiva E. Hill, Worcester,Mass., assignor to Norton Company, Worcester, Mass., a corporation ofMassachusetts Application February 8, 1954, Serial No. 408,899 10Claims. (Cl. 51-105) The invention relates to grinding machines and moreparticularly to a semi-automatic multiple wheel grinding machine.

One object of the invention is to provide a simple and thoroughlypractical multiple wheel grinding machine for simultaneously grinding aplurality of spaced portions on a work piece. Another object is toprovide a multiple wheel grinding machine which is semi-automatic inoperation. Another object is to provide an automatically actuated workloading apparatus for positioning a work piece to be ground in alignmentwith the work supporting centers before grinding and to remove a workpiece therefrom after a grinding operation has been completed. Anotherobject of the invention is to provide a mechanism for automaticallymoving the footstock center into operative supporting engagement withthe work piece. 'Another object of the invention is to provide means forautomatically positioning the work piece axially into a predeterminedrelationship with the grinding wheels. A further object of the inventionis to provide work steadying rests which are automatically moved intooperative supporting engagement with the work piece by and in timedrelation with the wheel feeding mechanism after the work piece has beenrough ground to a predetermined extent. Other objects will be in partobvious or in part pointed out hereinafter.

One embodiment of the invention has been illustrated in the drawings inwhich:

Fig. l is a plan view of a multiple wheel grinding machine;

Fig. 2 is a cross sectional view, on an enlarged scale, takenapproximately on the line 2-2 of Fig. 1, through the wheel feedingmechanism;

Fig. 3 is a plan view partly in section, on an enlarged scale, of thework loading mechanism;

, Fig. 4 is a cross sectional view, on an enlarged scale takenapproximately on the line the work loading mechanism;

Fig. 5 is a cross sectional view, on an enlarged scale, takenapproximately on the line 55 of Fig. 3, through the work loaderactuating mechanism; and

Fig. 6 is a combined hydraulic and electric diagram of the actuatingmechanisms of the machine and the controls therefor.

A multiple wheel grinding machine has been illustrated in the drawingscomprising a base 10 having a longitudinally movable work table 11slidably supported on a flat way 12 and a V-way 13 formed on the uppersurface of the base 10. The table 11 serves as a support for a headstock14 and a footstock 15 having centers 16 and 17 respectively forrotatably supporting a work piece to be ground. The headstock 14 may bedriven by an electric motor 18 mounted on the upper surface thereof.

A manually operable traverse mechanism may be provided which may be ofthe old and well known type such as, for example, that shown in theexpired U. S. patent to C. H. Norton No. 762,838 dated June 14, 1904, towhich reference may be had for details of disclosure not 44 of Fig. 3,through contained herein. A manually operable traverse wheel 19 isrotatably supported on the front of the machine base 10 for actuatingthe traversing mechanism (not shown) to position the table 11longitudinally relative to the base 10 The base 10 also serves as asupport for a transversely movable wheel slide 25 supported on atransversely arranged flat way 26 and a V-Way 27 formed on the uppersurface of the base 10. The wheel slide 25 rotatably supports a wheelspindle 28 which is journalled in suitable bearings (not shown). Thewheel spindle 28 is arranged to support a plurality of spaced grindingwheels 29, 29a, 29b, 29c and 29d. A driving mechanism is provided forthe wheel spindle 28 comprising an electric motor 30 mounted on the upersurface of a wheel guard 24. The motor 30 is provided with a motor shaft31 supporting a multiple V-groove pulley 32 which is connected bymultiple V-belts 33 with a multiple V-groove pulley 34 mounted on theright hand end of the wheel spindle 28 (Fig. 1).

A suitable feeding mechanism is provided for feeding the wheel slide 25transversely relative to the base 10. This mechanism may comprise arotatable feed screw 35 which meshes with or engages a rotatable feednut 36. The feed nut 36 is rotatably supported in a pair of spacedanti-friction bearings 37 and 38 which are supported in a housing 39depending from the underside of the wheel slide 25. The right hand endof the feed screw 35 (Fig. 2) is rotatably supported by a slidablymounted sleeve 40 which is journalled in a cylindrical aperture 41formed in the base 10. The left hand end of the feed screw 35 isprovided with a reduced cylindrical portion which is slidsupport a stopabutment 52a.

'this movement of the pawl 53, the lower end ably keyed within arotatable sleeve 42. The sleeve 42 is journalled in an anti-frictionbearing 43 which is supported by the base It). A rotatable shaft 44 isslidably keyed within the left hand end of the sleeve 42.

A manually operable feeding mechanism is provided for actuating the feedscrew 35 to cause a transverse feeding movement of the wheel slide 25.This mechanism may comprise a rotatable feed wheel 45 located on thefront of the machine base 10. The feed wheel 45 is arranged to rotate agear 46 meshing with a gear 47 which is mounted on a rotatable shaft 48.The shaft 48 also supports a gear 49 meshing with a gear 50. The gear 50meshes with a gear 51 mounted on the left hand end of the rotatableshaft 44. A stop abutment mechanism, is provided for positively stoppingthe rotary motion of the feed screw 35 thereby limiting the infeedingmovement of the grinding wheel 29. This mechanism may comprise amicrometer adjusting mechanism 45a carried by the feed wheel 45 which isarranged to adjustably The micrometer adjusting mechanism is an old andwell known mechanism, such as, for example that shown in the expired U.S. patent to C. H. Norton No. 762,838 dated June 14, 1904, and H. L.Swainey No. 2,639,563 dated May 23, 1953, to which reference may be hadfor details of disclosure not contained herein. It will be readilyapparent from the foregoing disclosure that a rotary motion of the feedwheel 45 will be transmitted through the gear mechanism above describedto impart a rotary motion to the feed screw 35 thereby transmitting atransverse feeding movement to the Wheel slide 25 and the grindingwheels 29, 29a, 29b, 29c and 29:1. The direction of rotation of the feedwheel 45 serves to determine the direction of the transverse movement ofthe wheel slide 25.

A cam 52 formed integral with the stop abutment is adjustably supportedon the feed wheel 45 and is arranged to engage a cam face formed on theupper end of a pawl 53 to rock the pawl 53 in a counter-clockwisedirection about its supporting pivot stud 54. During thereof rocks awayfrom the actuating roller of a normally closed limit switch LS7 andallows the limit switch to close. The closing of the limit switch closesa circuit in a manner to be hereinafter described to move the worksteadyrest shoes into operative engagement with the work piece beingground. The steadyrest shoes are moved in an operative position for thefinish grinding operation, just a short time before a stop abutment 52aon the feed wheel 45 engages the upper end of the stop pawl 53 to limitthe infeeding movement of the grinding wheel slide.

In order to cause a rapid transverse positioning movement of the wheelslide 25 relative to the base 10, a hydraulically operated mechanism isprovided comprising a fluid pressure cylinder 55 which contains aslidably mounted piston 56. The piston 56 is connected to the right handend of a piston rod 57, the left hand end of which is operativelyconnected to the sleeve 40. When fluid under pressure is passed througha pipe 58 into a cylinder chamber 59, the piston 56 together with thefeed screw 35 will be moved rapidly toward the left to impart acorresponding movement to the wheel slide 25 and the grinding wheels 29.During this movement, fluid within a cylinder chamber 60 may exhaustthrough a pipe 61. A feed control valve 62 is provided for controllingthe admission to and exhaust of fluid under pressure from the cylinder55.

A grinding wheel feeding mechanism may be provided for imparting a slowrotary motion to the feed screw 35 in a manner substantially identicalwith that shown in my prior U. S. Patent No. 2,648,171 dated August 11,1953, to which reference may be had for details of disclosure notcontained herein. This mechanism may comprise a cylinder 65 (Fig. 6)which contains a slidably mounted piston 66. The piston 66 is providedwith rack teeth 67 which meshes with a gear 68 mounted on a shaft 69.The shaft 69 also supports a gear 70 which meshes with the gear 47. Whenfluid under pressure is passed through a pipe 71 into the left hand endof the cylinder 65, the piston 66 will be moved toward the right toimpart a rotary motion to the feed screw 35 so as to cause a forwardfeeding movement of the wheel slide 25. During this movement of thepiston 66 fluid may exhaust from a chamber formed at the right hand endof the cylinder 65 through a pipe 72. The feed control valve 62 servesto simultaneously control the passage of fluid under pressure to boththe cylinder 55 and cylinder 65.

The feed control valve 62 is a piston type valve having a slidablymounted valve member 75 formed with a plurality of spaced integral valvepistons to form a plurality of spaced valve chambers 76, 77 and 78. Theslidably mounted valve member 75 is also provided with a central passage79. A pilot valve 80 is provided for controlling the shifting movementof the valve member 75. The pilot valve 80 is normally held in a righthand end position by means of a spring 81. Fluid under pressure passingthrough a pipe 82, passes through the pilot valve 80, through a passage83 into an end chamber 84 to shift the slidably mounted valve member 75toward the left (Fig. 6). During this movement of the valve member 75fluid within an end chamber 85 may exhaust through the pilot valve 80and out through an exhaust pipe 86. A solenoid S1 is provided which whenenergized serves to shift the pilot valve 80 into its left hand endposition so that fluid under pressure passing through the pilot valvepasses through a passage 87 into the end chamber 85 to shift theslidably mounted valve member 75 toward the right.

A backlash valve 88 is provided to control fluid exhausting from thefeed cylinder 65 to allow an initial rapid movement thereof to take upthe backlash in the gear train of the feed mechanism.

It is desirable to provide means to facilitate bypassing fluid from oneend of the said cylinder 65 to the other to facilitate a manualadjustment of the wheel slide 25. A manually operable rotary valve 90 isprovided having a control lever 91. In the position of the valve 90(Fig. 6) fiuid under pressure from a pressure pipe 92 passes through thevalve 90, through the pipe 82 to the pilot valve to control the shiftingmovement of the feed control valve 62. When it is desired to manuallyadjust the position of the wheel slide 25 by manual actuation of thefeed wheel 45, the control lever 91 is shifted in a counter-clockwisedirection into broken line position 91a. In this position of the valvefluid from the pressure pipe 92, passes through the valve 90, through apipe 93 into a chamber formed at the right hand end of a bypass valve94. The bypass valve 94 is a piston type valve comprising a slidablymounted valve member 95 which is normally held in its right hand endposition by means of a spring 96. In the position of the valve 94 (Fig.6) fluid under pressure from the feed control valve 62 passes through aball check valve and through a pipe 101, through the valve 94 and thepipe 72 into the chamber formed at the right hand end of the saidcylinder 65. Fluid within the right hand end chamber of the cylinder 65moves the piston 66 toward the left so that fluid within the left handend chamber of the cylinder 65 may exhaust through the pipe 71, throughthe valve 94, through the pipe 97 into the valve chamber 78, through thecentral passage 79 into the valve chamber 76 and exhaust through a pipe98. When it is desired to manually feed the wheel by actuation of thefeed wheel 45, the control lever 91 is shifted into position 91a so thatfluid under pressure is passed through the pipe 93 to cause the valvemember 95 to move toward the left so that both the pipe 71 and the pipe72 are connected with a valve chamber 99. In this position of the valve94, fluid may readily pass from one end of the cylinder 65 to the otherthereby facilitating a manual actuation of the feed wheel 45 foradjusting the wheel slide 25 and the grinding wheel 29.

A fluid pressure system is provided for supplying fluid under pressureto operate the various mechanisms of the machine. This system maycomprise a motor driven pump 100 which draws fluid through a pipe 101from a reservoir 102 and forces fluid under pressure through the pipe 92to the various mechanisms of the machine. A relief valve 103 isconnected to the pipe 92 to facilitate exhausting excess fluid underpressure from the system to maintain the desired operating pressuretherein.

A table traversing mechanism is provided for traversing the work table11 longitudinally to facilitate positioning a work piece to be groundrelative to the grinding wheel or wheels. This mechanism is preferably ahydraulically operated mechanism comprising a cylinder 105 which isfixedly mounted to the underside of the table 11. The cylinder 105contains a slidably mounted piston 106 which is connected to oppositelyextending hollow piston rods 107 and 108 respectively. The outer ends ofthe piston rods 107 and 108 are fixedly connected to brackets 109 and110 which are fixedly mounted on the machine base 10.

A solenoid operated reversing valve 111 is provided for controlling theadmission to and exhaust of fluid from the cylinder 105. The reversingvalve 111 as illustrated in Fig. 6 is shown in a central or neutralposition. When a solenoid S3 is energized, the valve 111 shifts towardthe right so that fluid under pressure in the pipe 92 may pass throughthe valve 111 and through a pipe 112,

through the hollow piston rod 108 into a cylinder chamber 113 to causethe cylinder 105 and the table 11 to move toward the right. During thismovement fluid within a cylinder chamber 114 may exhaust through thehollow piston rod 107, through a pipe 115, through the valve 111 and outthrough an exhaust pipe 116. Av throttle valve 117 in the exhaust pipe116 serves to control. the

speed of movement of the table 11 in either direction. Similarly when asolenoid S2 is energized, the valve 111 is moved toward the left so thatfluid under pressure from the pipe 92 passes through the valve 111,through the pipe 115, through the hollow piston rod 107 into thecylinder chamber 114 to cause the cylinder 105 and the table 11 to movetoward the left. The energization of the solenoids S2 and S3 isautomatically controlled in a manner to be hereinafter described.

As shown diagrammatically in Fig. 6, a table dog 118 is arranged toengage the actuating plunger of a limit switch LS4 to hold thecontactors in the position illustrated. As the table 11 moves toward theleft, a rod 340 which will be more fully described hereinafter isarranged to move into engagement with the actuating plunger of anormally open limit switch LS3.

A hydraulically actuated mechanism is provided for automaticallycontrolling actuation of the footstock 15. This mechanism may comprise acylinder 120 containing a slidably mounted piston 121. A piston rod 122is connected to the piston 121. The left hand end of the piston rod 122is slidably keyed within a sleeve within the footstock spindle andserves when moved toward the left to compress a spring 123 yieldably tomove the footstock center 17 into engagement with the work piece to beground. When fluid under pressure is passed through a pipe 124 into acylinder chamber 125, the piston 121 together with the footstock center17 will be moved toward the left, that is, toward an operative positionto support one end of the work piece. During this movement fluid withina cylinder chamber 126 may exhaust through a pipe 127.

A solenoid actuated control valve 128 is provided for controlling theadmission to and exhaust of fluid from the cylinder 120. The valve 128is preferably a piston type valve which is normally held in its lefthand end position by means of a spring 129.

A solenoid S4 is provided which when energized serves to shift the valve128 into its right hand end position.

In the position illustrated in Fig. 6, fluid under pressure from thepipe 92 passes through the valve 128, through the pipe 130, through thepipe 127 into the cylinder chamber 126 to cause a pressure against'theleft hand side of the piston 121. The piston 121 cannot move because theexhaust of fluid therefrom is blocked by a sequence valve 132 having aslidably mounted valve member 133. Thevalve member 133 is provided withspaced valve pistons forming a valve chamber 134. A check valve 135 isprovided integral with the sequence valve 132 and is connected to apassage 136. Fluid under pressure passing through the pipe 130 causes adownward movement of the valve membe'r'133 against the compression of anadjustable spring at the lower end thereof. When the valve member 133moves downwardly so as to uncover a port at the end of a pipe 131, fluidmay then exhaust from the cylinder chamber 125, through the pipe 124through the valve chamber 134, through the pipe 131, through the valve128 and out through an exhaust pipe 137. The exhaust pipe 137 contains athrottle valve 138 which regulates the return of exhaust of fluid fromthe cylinder chamber and thereby regulates the rate of movement of thefootstock center 17 toward an inoperative position.

When the solenoid S4 is energized and the valve 128 is shifted to itsright hand end position fluid under pressure from the pipe 92 may passthrough the pipe 131, through the passage 136 to open the check valveand then pass through the pipe 124 into the cylinder chamber 125 to movethe piston 121 toward the left thereby moving the footstock center 17toward the left into operative supporting engagement with the work pieceto be ground. During this movement fluid may exhaust from the cylinderchamber 126, through the pipe 127, through the pipe 130, through thevalve 128 and out through the pipe 137 and the throttle valve 138. Thethrottle valve 138 serves to control the rate of movement of thefootstock center 17 toward an operative position. The automaticactuation of thevalve 128 will be described hereinafter.

The footstock spindle is provided with rack teeth 140 which mesh with agear segment 141 which is supported to rotate on a stud 142. A member143 fixedly supported to rotate with the gear segment 141 is arranged tomove in the path of an actuating roller of a limit switch LS2 whichserves in a manner to be hereinafter described to start movement of thetable 11 toward the left.

The machine is provided with a pair of spaced work steadying rests and151 (Fig. 1) which are identical in construction, consequently only oneof the steady rests has been shown in detail. The steady rests comprisea steady rest base 152 which supports a pivot stud 153. A steady restarm 154 is mounted on the pivot stud 153 and is provided with a pair ofspaced adjustably mounted work steadying shoes and 156.

A hydraulically operated mechanism is provided for swinging the arm 154and the steady rest shoes 155 and 156 into operative engagement with awork piece being ground and to maintain it in engagement therewithduring the grinding operation. This mechanism may comprise a cylinder157 which contains a slidably mounted piston 158. The piston 158 isfastened to the lower end of a piston rod 159, the upper end of which isarranged to engage and swing the arm 154. A tension spring 160 servesnormally to maintain the arm 154 in operative engagement with the end ofthe piston rod 159. The steady rest base 152 is preferably adjustablyclamped onto a longitudinally movable slide 161 which is supported by aslide rod 162 and a slide bar 163. Both of the steady rest bases aresupported on the slide 161 and may be adjusted longitudinally thereon asdesired. The parts of the steady rests 150 illustrated in Figs. 1 and 6have been designated with the same numeral suffixed with the letter a.

it is desirable that the steady rest shoes 155 and 156 remain out ofengagement with the work piece during the initial grinding operation andthat they be moved automatically into engagement therewith for the finalor finishing portion of the grinding. This is preferably accomplished bymeans of a solenoid-actuated control valve 165. The valve 165 is apiston type valve having a slidably mounted valve member 167 normallyheld in a left hand end position by a spring 166. A solenoid S7 isprovided which when energized serves to shift the valve member 167toward the right. When the solenoid is energized, fluid from thepressure pipe 92 may pass through the valve 165, through a pipe 168,through a throttle valve 169 to both of the cylinders 157 and 157a tomove the steady rest arms 154 and 154a into an operative position withthe work steadying shoes in supporting engagement with the work piecebeing ground. The solenoid S7 is energized by the closing of thenormally closed limit switch LS7 when the work piece has been partiallyground I automatically to move the steady rest shoes into engagementwith the work piece and to maintain the shoes in engagement therewithduring the remainder of the grinding operation. When the feed wheel 45is turned in a clock- Wise direction during the resetting of the feedpiston 66, the limit switch LS7 is opened thereby deenergizing thesolenoid S7 so that fluid may exhaust from both of the cylinders 157 and157a thereby withdrawing the steady 7 rest shoes to inoperationpositions.

A multiple wheel truing apparatus is provided whereby all of thegrinding wheels may be simultaneously trued by means of a manuallyinitiated cycle. This truing mechanism is identical with that shown inmy copending application Ser. No. 358,337 filed May 29, 1953, to whichreference may be had for details of disclosure not contained herein.This mechanism may comprise a cross slide 186 which is supported onspaced parallel ways 181 v and 182 (Fig. 1) formed on the upper surfaceof the wheel slide 25. The cross slide is provided with a longitudinalextending dove-tailed slide way 183 for =-guiding a longitudinallytraversable slide 184. The

upper surface of the slide 184 is provided with a dovetailed slide way185 to which a plurality of truing tool units 186, 186a, 186b, 1860 and186d may be clamped in spaced adjusted positions thereon. Each of thetruing tool units are provided with a clamping block 187 to facilitateclamping the units in adjusted positions on the dove-tailed slide way185.

A suitable feeding mechanism is provided for adjusting the cross slide180 toward and from the wheel spindle 28. This mechanism may comprise afeed screw 190 which meshes with or engages a rotatable feed nut 191journalled in anti-friction bearings 192 and 193. A shaft 194 isslidably keyed within the feed screw 190. The left hand end of the shaft194 is rotatably supported in an anti-friction bearing 195 which servesto hold the shaft 194 against axial movement. The right hand end of thefeed screw 190 is journaled in an anti-friction bearing (not shown)within a piston 196. The nut 191 is provided with a spiral gear 197which meshes with a spiral gear 198. The spiral gear 198 is keyed onto arotatable shaft 199 the other end of which is provided with a manuallyoperable wheel 200. By rotation of the feed wheel 200, a rotary motionmay be imparted through the mechanism just described to rotate the feednut 191 thereby causing a transverse movement of the cross slide 180.

In order to cause a rapid positioning movement of the cross slide 180, ahydraulically operated mechanism is provided comprising the piston 196which is slidably mounted within a cylinder 202. The cylinder 202 isfixedly mounted on the wheel slide 25. The right hand end of the feedscrew 190 is formed as a piston rod for the piston 196. The feed screw190 may be moved in an axial direction by the piston 196 to cause arapid positioning movement of the cross slide 180, or may be rotated ina manner to be hereinafter described to impart a transverse movement tothe cross slide 180. When fluid under pressure is passed through a pipe205 into a cylinder chamber 201, the piston 196 will be moved toward theleft (Figs. 2 and 6) to impart a corresponding positioning movement tothe cross slide 180 so as to move the truing tool units 186, 18611,186b, 186:: and 186d into an operative position.

In the preferred construction, a separate independent hydraulicmechanism is provided for moving the cross slide 180 rearwardly to aninoperative position. This mechanism may comprise a cylinder 206 whichis fixedly mounted on the cross slide 180. The cylinder 206 contains aslidably mounted piston 207 which is connected to one end of a pistonrod 208. The right hand end of the piston rod 208 is fixedly connectedto a bracket 209 formed integral with the wheel slide 25. When fluidunder pressure is passed through a pipe 210 into a cylinder chamber 211,the piston 207 being anchored, the cylinder 206 moves toward the right(Figs. 2 and 6) to cause a rapid rearward movement of the cross slide180.

A manually operable rotary-type valve 212 is provided for controlilngthe admission to and exhaust of fluid from the cylinders 202 and 206.The valve 212 is provided with a manually operable control lever 213 bymeans of which the valve rotor 214 may be shifted so as to reverse theflow of fluid when desired. As illustrated in Fig. 6, fluid underpressure from the pressure pipe 92 passes through the pipe 210 into thecylinder chamber 211 to move the cross slide 180 into a rearward orinoperative position and to hold it in this position. When it is desiredto effect a truing operation, the lever 213 may be rocked in acounter-clockwise direction into the broken line position 213a (Fig. 6)so that fluid under pressure from the pipe 92 may pass through the pipe205 into the cylinder chamber 201 to cause a feed positioning movementto the cross slide 180.

A power operated traversing mechanism is provided for traversing thetruing tool slide 184 longitudinally in either direction. This mechanismmay comprise a feed screw 220 which is rotatably journalled in a bearing221 fixedly mounted on the cross slide 180. The feed screw 220 mesheswith or engages a nut 222 mounted on the left hand end of the slide 184(Fig. 1). A rotary-type fluid motor 223 is mounted on the cross slide180. The motor 223 is provided with a rotor shaft having a V-groovepulley 225 which is connected by a V-belt 226 with a V-groove pulley 227mounted on the left hand end of the feed screw 220. It will be readilyapparent from the foregoing disclosure that rotation of the motor shaftwill be imparted through the driving mechanism above described to rotatethe feed screw 220 and thereby impart a longitudlnal traversing movementto the slide 184. As shown diagrammatically in Fig. 6, the fluid motor223 is connected directly with the end of the feed screw 220.

A control valve 230 is provided for controlling the admission to andexhaust of fluid from the fluid motor 223 to control the longitudinalmovement of the slide 184. The control valve 230 is a fluid actuatedvalve controlled by a solenoid-actuated pilot valve 231 which is shiftedin opposite directions by means of a pair of solenoids S5 and S6. A pipe232 and a pipe 233 are connected between the control valve 230 and thefluid motor 223. The stroke of the longitudinally movable slide 184 isdetermined by a pair of spaced lugs 234 and 235 which are either formedintegral with or adjustably mounted on the longitudinally movable slide184. The lugs 234 and 235 are arranged to engage the actuating plungerof a pair of limit switches LS8 and LS9 respectively. A push buttonstart switch 236 is provided for starting the truing cycle and a stopswitch 237 is provided to stop the truing cycle at any time if desired.

In order to facilitate truing the grinding wheels a predetermined amountat each pass of the longitudinally movable slide 184, it is desirable toprovide an automatic compensator 240 which is arranged automatically torotate the feed screw 190 by a predetermined increment to advance thetruing apparatus cross slide and at the same time to rotate the wheelfeed nut 36 relative to the feed screw 35 to compensate for thereduction in diameter of the grinding wheels caused by the truingoperation, so that after a truing operation grinding may be resumedwithout the necessity of resetting the wheel feeding mechanism.

The feed compensator 240 may comprise a fluid motor 241 which issubstantially identical with that shown in the prior U. S. Patent No.2,522,481 to D. W. Martin, dated September 12, 1950, and the compensatoras a unit is substantially the same as that shown in the prior U. S.Patent No.'2,522,485 to H. A. Silven and C. G. Flygare dated September12, 1950, to which reference may be had for details of disclosure notcontained herein. A pipe 242 connects with the pipe 232 and a pipe 243connects with a pipe 233 so that when the control valve 230 is actuatedto start the traverse motor 223 of the wheel truing apparatus, fluid isalso passed to the compensator motor 241 to impart a compensatingadjustment thereto.

The fluid motor 241 is connected by an arm 244 to actuate a pawl andratchet mechanism to impart an incremental rotary motion to a shaft 246.The shaft 246 is provided with a bevel gear 247 which meshes with abevel gear 248 mounted on a vertically arranged rotatable shaft 249. Thelower end of the shaft 249 is provided with a worm 250 which meshes witha worm gear 251 formed on the periphery of the rotatable feed nut 36.The upper end of the shaft 249 is provided with a worm 252 which mesheswith a worm gear 253 mounted on the left hand end of the shaft 194. Itwill. be readily apparent from the foregoing disclosure that theactuation of the pawl and ratchet mechanism 245 will be imparted throughthe mechanism just described to impart a compensating adjustment to thefeed screw of the truing apparatus and a corresponding compensatingadjustment of the rotatable feed nut 36. This compensating adjust mentadvances the truing tool cross slide 180 by a desired and predeterminedamount for a truing operation and at the same time imparts acompensating adjustment to the wheel slide feeding mechanism so thatafter a grinding wheel truing operation, grinding may be resumed withoutthe necessity of resetting or adjusting the wheel feed mechanism.

A fluid pressure actuated by-pass valve 255 is provided for controllingthe admission to and exhaust of fluid from the compensator motor 241.The by-pass valve 255 is a piston type valve having a plurality ofspaced valve chambers 256, 257 and 258. A compression spring 259 servesnormally to hold the valve 255 in a left hand end position. In thisposition of the valve fluid under pressure may pass from the pipe 232,through the valve chamber 257 into the pipe 242. Similarly the fluidwithin the pipe 233 may pass through the chamber 258 into the pipe 243so that when the valve 230 is shifted to change the direction ofmovement of the fluid motor 223, fluid will also be passed through thepipes 242 and 243 to reverse the direction of flow of fluid to thecompensator motor 241. The pipe 93 is connected to the left hand end ofthe by-pass valve 255 so that when the control lever 91 is shifted in acounter-clockwise direction into position 91a to actuate the by-passvalve 94, fluid will also pass through the pipe 93 to actuate theby-pass valve 255. Fluid under pressure passing through the pipe 93shifts the valve 255 into a right hand end position so that fluid mayby-pass from the pipe 232, through the valve chamber 256 into the pipe233 thereby allowing a by-passage of fluid between opposite sides of thefluid motor 23 and also between opposite sides of the compensator motor241. This by-pass of fluid between opposite sides of the motors 223 and241 serves to facilitate manual adjustment of the longitudinaltraversing movement of the slide 184 and also of the compensator motor241.

Each of the truing tool units 186, 186a, 186b, 1860 and 186d is providedwith truing tools 260, 260a, 260b, 2600 and 2600! respectively. Thetruing tools 260 are mounted on a transversely movable member (notshown) which is identical with that shown in my copending applicationSer. No. 358,337 filed May 29, 1953, to which reference may be had fordetails of disclosure not contained herein. A follower 261 is providedon each of the transversely movable truing tools of each of the units186, 186a, 186b, 1860 and 186d. The followers are arranged to ride upona forming bar 262 the ends of which are fastened to the transverselymovable slide 180. The forming bar serves to control the path ofmovement of the truing tools. The forming bar may be formed as a planesurface or may be shaped if shaped faces are provided on the grindingwheels.

An independent feed adjusting mechanism 263, 263a, 263b, 2630 and 263don the truing tool units 186, 186a, 186b, 1860 and 186d respectively tofacilitate independently adjusting the position of the truing toolsrelative to each of the units. A hydraulic mechanism is provided foractuating the said adjusting mechanism 263 in a manner identical withthat disclosed in my copending application above referred to. Each ofthe truing tool units is provided with a cylinder 264, 264a, 264b, 2640and 264d respectively which contain slidably mounted pistons 265, 265a,265b, 2650 and 265d. A control valve 266 is operatively connected tocontrol the admission to and exhaust of fluid from the cylinders 265 and265a. When solenoid S is energized by actuation of a push button switch269, the valve 266 will be shifted toward the left so as to pass fluidinto the cylinder 264 to provide a compensating adjustment to the truingtool 260. Similarly when a solenoid S11 is energized by closing a pushbutton switch 269a, the valve 266 will be shifted toward the right so asto pass fluid to the cylinder 264a to provide a compensating adjustmentof the truing tool 260a.

A control valve 267 is provided for controlling the passage of fluidunder pressure to the cylinders 26412 and 2640. When a solenoid S12 isenergized by closing a push button switch 269b, the valve 267 will beshifted toward the left to pass fluid into the cylinder 264 but toimpart a compensating adjustment to the truing tool 26%. Similarly whenthe solenoid S13 is energized by closing a push button switch 2690, thevalve 267 will be shifted toward the right so that fluid under pressurewill be passed to the cylinder 2640 to impart a compensating adjustmentto the truing tool 2600. v A control valve 268 is provided forcontrolling the passage of fluid to the cylinder 264d. When a solenoidS14 is energized by closing of a push button switch 269d, the valve 268will be shifted toward the left so that fluid under pressure will bepassed to the cylinder 264d to impart a compensating adjustment to thetruing tool 260d. The mechanism just described provides a remote controlwhereby any of the truing tools may be independently advanced by apredetermined increment to compensate ,for differential in wheel wear.It will be readily apparent from the foregoing disclosure that theactuation of the push button switches 269, 269a, 269b, 2690 and 269dwill be imparted, in a manner more fully described in my copendingapplication, to impart compensating adjustments to the truing tools 260,260a, 260b, 2600 and 260d.

A plurality of dial-type work gages 275, 275a, 275b, 2750 and 275d areprovided for independently gaging spaced portions of the work pieceduring grinding. Each of the dial gages is located opposite the grindingwheel and is arranged to engage the work piece 21 as shown in Fig. 2.These dial gage units are standard commercial units and it is,therefore, not believed necessary to further illustrate or describethem. If the wheel slide is fed toward the work axis to grind aplurality of spaced portions on the work piece 21, the operator observesthe readings of the dial indicator 275. If the dial indicators show thatone or more wheels require truing to produce predetermined diameters,the grinding operation may be stopped and the wheel truing apparatusmoved to an operative position after which one or more of the pushbutton switches 269, 269a, 269b, 2690 or 269d may be actuated to imparta compensating adjutstment to one or more of the truing tools 260. Afterthe compensating adjustment has been made the truing apparatuslongitudinally movable slide 184 may be traversed longitudinally to passthe truing tools across the operative faces of the grinding wheels totrue the same to the desired and predetermined extent.

A work positioning mechanism is provided to facilitate positioning thework piece being ground axially into a predetermined position relativeto the grinding wheels. As illustrated in Fig. 3, the shaft 162 issupported by a plurality of spaced brackets 280, 281 and 282 which areadjustably clamped onto the work table 11. The shaft 162 is supported inbrackets 280 and 281 so that it is free to rotate and move axiallyrelative thereto. The bracket 280 is provided with spaced needlebearings 283 and 284 to support the left hand end of the shaft 162. Anaxial type ball bearing 285 is provided between the needle bearings 283and 284 to facilitate an axial movement of the shaft 162 relative to thebracket 280.

Similarly the bracket 281 is provided with a pair of spaced needlebearings 286 and 287 between which is located an axial-type ball bearing288 for supporting the right hand end of the shaft 162 for both a rotaryand axial movement.

The slide 161 is provided with a pair of spaced antifriction bearings289 and 290 which serve to maintain the shaft 162 in a predeterminedposition relative to the slide 161. The right hand end of the shaft 162is provided with a tri-lobe portion which is slidably keyed within acorrespondingly shaped aperture formed in a gear 292 (Figs. 3 and 5).The gear 292 is rotatably supported by a pair of spaced anti-frictionbearings 293 and 294 keyed by the bracket 282.

The shaft 162 forms the actuating shaft for a work loading mechanismcomprising a pair of spaced work loader arms 300 and 301. Both of thesearms are identical in construction; consequently only one of the armshas been illustrated in detail in Figs. 4 and 5. The Work loader arm 300comprises an arm 302 which is provided with an integral boss or hub 303which is adjustably clamped to the shaft 162. The arm 302 is providedwith a work supporting surface 304 which supports a work piece 21 whenthe loader arms are swung into inoperative position, that is, in aclockwise direction (Figs. 4 and 5). In an operative position, the arm302 is positioned by an adjustable stop screw 305 which moves intoengagement with a surface of the work table 11. By adjustment of thestop screw 305, the surface 304 may be adjusted to position the workpiece 21 in axial alignment with the work supporting centers 16 and 17.The arm 302 pivotally supports an arm 306 which is connected to the arm302 by a pivot stud 307. The arm 306 is provided with a work supportingsurface 308 (Fig. 4) which supports a work piece 21 when loaded into themachine. A compression spring 309 is interposed between the right handend of the arm 306 (Fig. 4) and the upwardly extending boss formedintegral with the arm 302. The spring 309 tends to rock the arm 306 in aclockwise direction relative to the arm 302 so as to hold the work piecein position on the loader arms 300 and 301 as they are swung from aloading into an operative position. As illustrated in Fig. 4, when thearm 300 is swung into a loading position, a stop surface 310 on the arm306 engages a surface formed on the upper portion of the table 11 so asto rock the arm 306 in a counter-clockwise direction to separate thework supporting surface 308- 304 to facilitate loading a work piece 21therein. When the loader arms 300 and 301 are moved in a clockwisedirection (Figs. 4 and 5) as the stop surface 310 moves out ofengagement with the table 11, the compression of the spring 309 servesto rock the arm 306 so that the work supporting surfaces 308 and 304approach each other to hold the work piece to be ground on the loaderarms during a loading operation.

A fluid pressure operated mechanism is provided which is actuated by andin timed relation with the other mechanisms of the machine to actuatethe loader arms 300 and 301. This mechanism may comprise a cylinder 315(Figs. 5 and 6) which is formed integral with the bracket 282. Thecylinder 315 contains a slidably mounted piston 316 having racked teeth317 formed on the lower surface thereof which mesh with the gear 292.When fluid under pressure is passed through a pipe 318 into a cylinderchamber 319, the piston 316 will be moved toward the right to impart aclockwise rotary motion to the gear 292, to the shaft 162, to the loaderarms 300 and 301 to shift a work piece 21 from the loading positionillustrated in Fig. 4 into an operative position illustrated in Fig. 5with the axis of the work aligned with the axis of the work supportingcenters 16 and 17. During this movement of the piston 316 fluid Within acylinder chamber 320 may exhaust through a pipe 321. Similarly when thedirection of flow of fluid under pressure is reversed and fluid underpressure is passed through the pipe 321, the piston 316 will be movedtoward the left to impart a counterclockwise rotary motion to the workloader mechanism to shift a ground work piece 21 from the positionillustrated in Fig. 5 into the position illustrated in Fig. 4.

A solenoid-actuated control valve 325 is provided for controlling theadmission to and exhaust of fluid from the cylinder 315. The valve 325is normally held in its left hand end position by means of a spring 326.A solenoid S9 is provided which when energized serves to shift the valve325 toward the right so as to reverse the flow of fluid under pressureto the cylinder 315.

The shaft 162 is provided with a collar 330 adjustably mounted on theleft hand end thereof. The collar 330 is provided with a stud 331 whichis arranged in the path of an actuating roller of a limit switch LS1.

It is desirable to provide a positioning mechanism to position the Workpiece together with the table 11 so that the portions of the work pieceto be ground are in a predetermined relationship with the grindingwheels.

As illustrated in Figs. 3 and 4, an upwardly extending bracket 335 ismounted on the slide 161. The bracket 335 is provided with a pair ofspaced bosses 336 and 337 which are arranged to be engaged by ashouldered locating surface 338 on the work piece 21. The slide 161 isprovided with a bracket 339 which supports a rod 340. The rod 340 may beadjusted longitudinally relative to the bracket 339 and clamped inadjusted position relative thereto by means of a pair of nuts 341 and342.

When the footstock center is moved toward the left into operativeengagement with the work piece, continued movement of the footstockcenter 17 toward the left shifts the work piece 21 axially towardsupporting engagement with the headstock center 16. During this movementthe surface 338 on the work piece moves into engagement with bosses 336and 337 after which the bracket 335 together with the slide 161 and theshaft 162 moves toward the left against the compression of a spring 343.When the slide 161 moves toward the left, the rod 340 moves intoengagement with an adjustable stop screw 344 carried by a rock arm 345which is pivotally supported by a stud 346. The screw 344 is arranged toengage the actuating plunger 347 of a dial indicator 348. The rock arm345 is provided with an adjustable stop screw 349 which is arranged tomove in the path of an actuating plunger 350 of a normally open limitswitch LS3. The indicator 348 together with the stud 346 and the limitswitch LS3 are supported on a bracket 351 which is in turn supported bya bracket 352 fastened to the front of the machine base. The movement ofthe table 11 toward the left to position the work piece 21 relative tothe grinding wheels 29 continues until the limit switch LS3 is closed soas to stop the longitudinal movement of the table 11 in a manner to behereinafter described with the portions of the work pieces to be groundlocated opposite to the grinding wheels.

In order to drive the work piece 21, the headstock 14 is provided with aspring pressed driving plunger 355 which is carried by a rotatable faceplate 356. When the work piece 21 is moved into supporting engagementwith the headstock center, the spring pressed work driving plunger 355engages a flange surface adjacent to the left hand end of the work pieceuntil the face plate rotates so that the plunger 355 may slide intodriving engagement with a notch 357 formed in the peripheral portion ofthe flange on the work piece 21.

As shown in Fig. 6 a switch 360 is provided for starting the wheeldriving motor 30. A switch 361 is provided for starting the motor drivenpump 100. A cycle control lever 365 is pivotally supported on the frontof the machine base. The lever 365 is arranged when located in acounter-clockwise direction to actuate a cycle start switch 366, or whenmoved in a clockwise direction to actuate a cycle stop switch 367.

Operation The operation of this improved grinding machine will bereadily apparent from the foregoing disclosure. When electric current isturned on, with the table 11 in a right hand end position (as shown inFig. 6) the relay switch CRIS is energized. The switch 360 is manuallyclosed to start the wheel drive motor 30. The switch 361 is manuallyclosed to start the motor driven fluid pump 100. A work piece 21 is thenpositioned in the loader arms 300 and 301 as shown in Fig. 4.

The cycle control lever 365 is then rocked in a counter-clockwisedirection to close the cycle start switch 366 which serves to close acircuit to energize a relay switch CRll. The energizing of relay switchCRll closes a normally open contactor to energize solenoid S9 to shiftthe valve 325 toward the right so that fluid under pressure from thepressure pipe 92 passes through the valve 325 through the pipe 318 intothe cylinder chamber 319 to move the piston 316 toward the right therebyswinging the loader arms 300-301 in a clockloader arms to an operativeposition momentarily closes the limit switch LS1. The closing of thelimit switch LS1 serves to energize a relay switch CR12.

A normally closed limit switch LS6, being closed sets up a holdingcircuit to hold the relay switch CH12 energized. The energizing of relayswitch CR12 closes a circuit to energize the solenoid S4 to shift thevalve 128 toward the right so that fluid under pressure from thepressure pipe 92 may pass through the pipe 131 through the passage 136in the sequence valve 132. The fluid under pressure in the passage 136opens the check valve 135 and passes fluid under pressure through thepipe 124 into the cylinder chamber 125 to move the piston 121 toward theleft to advance the footstock center 17 toward the left into engagementwith the right hand end of the work piece 21. Continued movement of thefootstock center 17 toward the left shifts the work piece toward theleft so that the left hand end thereof approaches the headstock center16. During this movement a shouldered face 338 on the work piece 21engages the bosses 336 and 337 on the bracket 335 and continued movementthereof moves the slide 161 together with the shaft 162 toward the leftagainst the compression of the spring 343. The movement of the footstockcenter 17 toward the left serves through the arm 143 to actuate thelimit switch LS2 which serves to close a circuit to energize a relayswitch CHIS. The energizing of the relay CH13 serves to close a circuitthrough the switch 372 to energize a relay switch CR3b and at the sametime to energize the solenoid S2 to shift the valve 111 toward the leftso that fluid under pressure from the pressure pipe 92 may pass throughthe pipe 115, through the piston rod 107 into the cylinder chamber 114to start the cylinder 113 and the table 11 moving toward the left.Movement of the table toward the left continues until the rod 344)engages the screw 344 to rock the rock arm 345 in a counterclockwisedirection thereby swinging the screw 349 away from the actuating plunger350 of the normally closed limit switch LS3 so as to allow the switchLS3 to close. The closing of the limit switch LS3 closes a circuit toenergize a relay switch CR14. When the relay switch CR14 is energized, anormally closed contactor therein breaks a circuit so as to deenergizethe relay switch CR3b to deenergize the solenoid S2 thereby allowing thecontrol valve 111 to return to a central position. This movement servesto precisely position the table 11 and the work piece 21 inpredetermined relationship with the grinding wheels 29.

The energizing of the relay switch CRM serves to close a normally openedcontactor therein to energize the electric timer 370. The energizing fthe timer 37d closes a circuit to start the work driving motor 13. Theface plate 356 rotates with the drive pin 355 yieldably engaging the endface on the work piece 21 until the drive pin engages a notch 357 formedin the work piece to rotate the work piece for a grinding operation. Theenergizing of the timer 370 also serves to energize the solenoid S1 toshift the control valve 62 toward the right to pass fluid under pressureinto the cylinder chamber 59 to cause a rapid approaching movement ofthe piston 56 together with the wheel slide 25 and the grinding wheels29. At the same time fluid is passed through the by-pass valve 94,through the pipe 71 into the fee-cl cylinder 65 to start the feed piston66 moving toward the right (Fig. 6). The movement of the piston 66toward the right serves through the gear mechanism previously describedto impart a rotary motion to the feed screw 35 so as to advance thewheel slide 25 and the grinding wheels 29 to grind spaced portions on awork piece to a predetermined size. Durin the grinding operation,rotation of the feed wheel 45 serves to move the cam 52 into engagementwith a cam face on the pawl 53 to rock the pawl 53 in a counterclockwisedirection thereby allowing the normally closed limit switch LS7 toclose. The closing of the limit switch LS7 takes place before thegrinding operation has been completed to energize the solenoid S7thereby shifting the control valve 165 toward the right so that fluidunder pressure from the pressure pipe 92 may pass through the pipe 168to the steady rests 159 and 151 to move the work steadying shoes thereofinto operative supporting engagement with the Work piece during thefinish grinding operation.

When the wheel slide 25 approaches its forward position, it opens anormally closed limit switch LS6 to break the holding circuit so as todeenergize the relay switch CR12. At the same time the limit switch LS6is opened, the timer 370 times out to break a circuit to deenergize thesolenoid S1 to cause a shifting of the control valve 62 so as to movethe piston 56 together with the Wheel slide 25 and the grinding wheels29 to a rearwardor inoperative position. At the same time fluid underpressure is reversed to the cylinder 65 to reset the piston 66 for thenext grinding operation. At the same time the timer 370 times out itbreaks a circuit to stop the work drive motor 18.

When the wheel slide 25 reaches a rearward or inoperative position itcloses a normally open limit switch LS5 which energizes a relay switchCR3a to energize the solenoid S3 to shift the control valve 111 towardthe right so that fluid under pressure from the pressure pipe 92 maypass through the pipe 112 into the cylinder chamber 113 to start thecylinder together with the table 11 moving toward the right. When thetable 11 approaches the right hand end of its stroke, it actuates thelimit switch LS4 to open the normally closed contactors therein so as todeenergize the solenoid S4 thereby allowing the released compression ofthe spring 129 to return the valve 128 to the position illustrated inFig. 6. In this position of the valve 128 fluid under pressure from thepipe 92 may pass through the pipe 130 into the cylinder chamber 126 andalso into the upper end of the sequence valve 132. The piston 121 cannotstart movement toward the right until the sequence valve chamber 134moves downwardly so that fluid may exhaust from the cylinder chamberthrough the pipe 124 through the chamber 134 and out through the pipe131. Movement of the footstock center 17 toward the right into aninoperative position serves to withdraw the arm 143 thereby allowing thenormally open limit switch LS2 to open thereby breaking a circuit todeenergize the relay switch C1213.

When the table 11 reaches the right hand end of its stroke, it closesthe normally open contactors of the limit switch LS4 to energize therelay switch CRIS. The normally closed contactor of the relay switchCRlS opens to break a circuit thereby deenergizing the solenoid S9thereby releasing the compression of the spring 326 to return the valve325 to the position illustrated in Fig. 6. In this position of the valve325 fluid from the pressure pipe 92 may pass through the valve 325.through the pipe 321 into the cylinder chamber 320 to move the piston316 toward the left thereby rocking the shaft 162 together with theloader arms 3t)t 31 in a counter-clockwise direction to move the groundshaft 21 from the position illustrated in Fig. 5 into the loadingposition as illustrated in Fig. 4. The ground shaft 21 may then beremoved from the motor arms Nth-391 and a new shaft to be groundinserted there instead. The cycle control lever 365 may then be againactuated to start the next cycle of operation.

In setting up the machine, it may be desirable to actuate the feedmechanism manually. The control lever 91 may be shifted in acounterclockwise direction into position 91a to shift the rotor of thevalve 90 so that fluid under pressure is passed through the pipe 93 toshift the by-pas s valve 94 toward the left (Fig. 6) so that fluid mayreadily by-pass between'the pipes '71 and 72 in order to facilitate amanual rotation of the feed wheel 45 without the necessity of overcomingthe fluid within the system.

A truing apparatus has been provided for simultaneously truing all ofthe grinding wheels 29 when desired. The control lever 213 is shifted ina counter-clockwise direction position 213a so that fluid under pressureis passed through the pipe 205 into the cylinder chamber 201 to move thecross slide 180 together with the entire truing apparatus toward theleft (Fig. 6) so that the truing tools 260 are in an operative positionrelative to the grinding wheels. The truing tools may remain in thisposition during a grinding cycle if desired. When it is desired to trueall of the grinding wheels, the push button switch 236 is closed toenergize a relay switch CR2a to energize the solenoid S5 therebyshifting the pilot valve 231 toward the right to pass fluid under pressure to shift the control valve 230 toward the left so that fluid underpressure is passed through the pipe 233 to start rotation of the motor223 which in turn serves to impart a rotary motion to the feed screw 220thereby traversing the longitudinally movable slide 184 tosimultaneously pass the truing tools 260 across the peripheries of allthe grinding wheels 29. At the same time fluid under pressure passingthrough the pipe 233 passes through the valve 255 and through the pipe242 to the compensator motor 241 to impart a compensating adjustment tothe shaft 246 thereby imparting a rotary motion to the feed screw 190 toadvance the cross slide 180 by a predetermined increment and at the sametime to impart a compensating rotary adjustment to the feed nut 36 whichadvances the wheel slide by an amount equal to the advance of the crossslide 180 so that after a truing operation, the grinding operation maybe resumed without the necessity of resetting or readjusting the wheelfeed mechanism. The longitudinal movement of the slide 184 is controlledby a pair of lugs 234 and 235 which are arranged to actuate the limitswitches LS8 and LS9 respectively. When the truing operation is started,the slide 184 traverses toward the right (Fig. 6) until the lug 235actuates the limit switch LS9. As the lug 234 moves away from theactuating plunger of the limit switch LS8, the normally closed contactstherein are closed to energize a relay switch CR8. When the slide 184reaches the right hand end of its stroke it actuates the limit switchLS9 to close the normally open contacts thereof thereby closing acircuit to energize the relay CR9. The energization of the relay switchCR9 closes normally open contactors therein to energize the solenoid S6thereby reversing the direction of fiow of fluid to the motor 233 tostart rotation of the feed screw 220 in the opposite direction to startthe traversing movement of the slide 184 toward the left. When the valve230 is shifted at the right hand end of the stroke of the slide 184,fluid under pressure is passed through the pipe 233 to the motor 223 andat the same time is passed through the pipe 243 to actuate thecompensating motor 241 thereby imparting a compensating adjustment tothe shaft 246. After one complete reciprocation of the slide 184, thatis two passes of the truing tools 26!) across the peripheries of thegrinding Wheels 29, the truing apparatus is automatically stopped. Ifadditional truing is desired, the truing start switch 236 may again beactuated to cause the truing apparatus to complete a second cycle ofoperation.

If during grinding it is found that one or more of the wheels arewearing unevenly, the grinding operation may be stopped and the wheelslide returned to an inoperative position after which any one of thepush buttons 269, 269a 269b, 2690 or 269d may be actuated to impart acompensating adjustment to one or more of the truing tools 260 afterwhich the push button switch 236 may be actuated to cause areciprocation of the truing tools across the peripheries of the wheels.Only the truing tools 260 that have been advanced by closing one or moreof the switches 269 will perform any truing operation on the respectivewheels.

It will thus be seen that there has been provided by this inventionapparatus in which the various objects hereinabove set forth togetherwith many thoroughly practical advantages are successfully achieved. Asmany possible embodiments may be made of the above invention and as manychanges might be made in the em bodiment above set forth, it is to beunderstood that all matter hereinabove set forth, or shown in theaccompanying drawings, is to be interpreted as illustrative and not in alimiting sense.

I claim:

1. In a grinding machine having a base, a transversely movable rotatablegrinding wheel thereon, a longitudinally movable work table on saidbase, a rotatable work support on said table including a headstock and afootstock each having work supporting centers for supporting oppositeends of a work piece to be ground, means to move said footstock centertoward and from the headstock, a pivotally mounted work loader having apair of spaced work supporting arms, a rock shaft on said table tosupport said loader, a fluid motor on said table, and a rack and gearmechanism interposed between the motor and rock shaft whereby said motorserves to rock said shaft to swing said loader in one direction toposition a work piece to be ground in axial alignment with the worksupporting centers before a grinding operation and to swing said loaderin the opposite direction to remove a work piece therefrom after agrinding operation has been completed.

2. In a grinding machine, as claimed in claim 1, in combination with theparts and'features therein specified in which movement of the footstockcenter serves to move the work piece axially into engagement with theheadstock center, means including a limit switch actuated by and intimed relation with the movement of the footstock center to start alongitudinal positioning movement of the table, and means including aslidably mounted member on said table which is engaged by said workpiece and is operatively connected to stop the longitudinal movement ofthe table when the work piece is positioned in a predetermined positionrelative to the grinding wheel.

3. In a grinding machine, as claimed in claim 1, in combination with theparts and features therein specified in which movement of the footstockcenter serves to move the work piece to be ground into axial engagementwith the headstock center, means including a limit switch actuated byand in timed relation with the movement of the footstock center to starta longitudinal positioning movement of the table, means including aslidably mounted member on said table having means coacting with alocating surface on the work piece to be ground during movement of thefootstock center, and means including a limit switch actuated by saidmember to stop the positioning movement of said table when the workpiece reaches a predetermined position relative to the grinding wheel.

4. In a grinding machine having a base, a transversely movable wheelslide thereon, a rotatable grinding wheel on said slide, alongitudinally movable table, a rotatable work support thereon includinga headstock and a footstock each having a work supporting center, meansfor moving the footstock center toward and from the headstock to move awork piece axially into engagement with the headstock center and tosupport the work piece during a grinding operation, means to traversesaid table longitudinally, means to feed said wheel slide transversely,a transversely movable work loader on said table, means to move saidloader automatically to position a work piece to be ground into axialalignment with the work supporting centers, and a cycle controlmechanism including a manually operable lever, means responsive toactuation of said lever to move said loader into an operative position,means responsive to movement of said loader to move said footstockcenter into operative engagement with the work piece and move it intoengagement with the headstock center, means responsive to movement ofsaid footstock center to initiate a longitudinal positioning movement ofthe table to facilitate positioning a work piece in a predeterminedrelationship with the grinding wheel, means responsive to said lattermovement to stop the longitudinal movement of the table when the workpiece is moved to a predetermined position relative to the grindingwheel, means responsive to said longitudinal positioning movement toenergize a timer to start the work drive motor and to initiate aninfeeding movement of the grinding wheel slide, and means responsive tosaid timer after a predetermined grinding operation to withdraw saidgrinding wheel to an inoperative position, to withdraw said footstockcenter to an inoperative position and thereafter to move said workloader to transfer the ground piece of work to an inoperative position.

5. In a grinding machine having a base, a transversely movable wheelslide thereon, a longitudinally movable table on said base, a rotatablework support thereon, a steady rest on said table having work steadyingshoes, means to move said shoes to and from an operative position, awheel feeding mechanism including a rotatable feed wheel to feed thewheel slide transversely in either direction, means including a stoppawl to limit the rotary motion of the feed wheel and the infeedingmovement of said slide, and means including a limit switch actuated byand in timed relation with said feed mechanism to move said steady restshoes into operative engagement with the work during the finish grindingoperation.

6. In a grinding machine having a base, a transversely movable wheelslide thereon, a longitudinally movable work table on said base, arotatable work support thereon, a steady rest on said table having worksteadying shoes, means including a piston and cylinder to move saidshoes to and from an operative position, a control valve therefor awheel feeding mechanism including a rotatable feed wheel to feed saidslide transversely in either direction, an adjustable stop abutment onsaid feed wheel, means including a stop pawl arranged to be engaged bysaid abutment to limit the infeeding movement of said slide, and meansincluding a limit switch actuated by and in timed relation with movementof said stop pawl to actuate said control valve so as to admit fluidunder pressure to move the steady rest shoes into operative engagementwith the work during the finish grinding operation.

7. In a grinding machine as claimed in claim 6, in combination with theparts and features therein specified of a cam on said stop abutmentwhich is arranged to rock said stop pawl, and electrically controlledmeans actuated by said stop pawl to move the steady rest shoes into anoperative position during the finish grinding operation.

8. In a grinding machine as claimed in claim 6, in combination with theparts and features therein specified in which the adjustable stopabutment is provided with a cam to rock said pawl before the feed wheelis stopped, a limit switch actuated by movement of said pawl, asolenoid-actuated control valve controlled by said limit switch to admitfluid under pressure to the steady rest cylinder to move the steady restshoes into operative engagement with the work piece during the finishgrinding operation.

9. In a grinding machine, as claimed in claim 1, in combination with theparts and features therein specified in which the rock shaft is arrangedparallel to the axis of the work centers, a pair of spaced arms on saidrock shaft each having a work supporting surface, a pivotally mountedjaw on each of said arms, yieldable means normally to swing said jawtoward said surface to hold a work piece on said arms during a loadingand unloading operation, and a stop surface on said jaws which movesinto engagement with said table when the loader is swung to a workloading position to rock said jaws relative to said loader arms so as tofacilitate a loading operation.

10. In a grinding machine, as claimed in claim 1, in combination withthe parts and features therein specified in which the rock shaft of thework loader is arranged parallel to the axis of the work centers, a pairof spaced arms on said shaft each having a work supporting surface, apivotally mounted jaw on each of said arms, yieldable means normally toswing said jaws toward said surface to hold a Work piece on said armsduring a loading and unloading operation, an adjustable stop on saidloader to facilitate positioning the loader and work piece so that thework piece is in axial alignment with the work supporting centers, and astop surface on each of said jaws which moves into engagement with saidtable when the loader is suwng to a loading position to rock said jawsrelative to said arms so as to facilitate a loading operation.

References Cited in the file of this patent UNITED STATES PATENTSRe.21,582 Klingele Sept. 24, 1940 1,662,546 Steiner Mar. 13, 19281,744,587 Steiner Jan. 21, 1930 2,105,841 Ott Jan. 18, 1938 2,229,312Silven Ian. 21, 1941 2,264,160 Flygare Nov. 25, 1941 2,313,482 RocksMar. 9, 1943 2,517,193 Fraser Aug. 1, 1950 2,638,719 Balsiger May 19,1953

